Hermetically sealed electrical connector



Oct. 31, 1961 R. w. MARTIN 3,007,130

HERMETICALLY SEALED ELECTRICAL CONNECTOR Filed Aug. 13, 1956 INVENTOR.

- 46 40 5 44 48 gaerzi g wzq diw/w/zegq United States Patent 3,007,130 7 HERMETICALLY SEALED ELECTRICAL CONNECTOR Robert Wesley Martin, Reserla, Califl, assignor to Technology Instrument Corporation of Acton, a corporation of Massachusetts Filed Aug. 13, 1956, Ser. No. 603,625 2 Claims. (Cl'. 339-192) This invention relates to an improvement in electrical connectors, and more specifically to an hermetically sealed connector adapted for use in and with plug-in electrical components wherein both the component and the equipment into which the component is plugged must be hermetically sealed against the surrounding atmosphere.

In order to insure secure electrical contact at all times, it is important that at least one of the mating connector members be of a highly resilient material acting as a spring. The hermetic sealing of a rigid'contact member into a plug or socket header is easily accomplished by the use of an ordinary glass-to-metal seal, wherein the metal conductor employed is of the same coefiicient of expansion as the glass insulator. However, in the case of the resilient member, the problem is far less simple, since the metals suitable for glass-to-metal seals do not possess the resiliency required for a secure spring contact. It is a further requirement, in general, that the resilient contact (usually installed in the permanent equipment because of cost considerations) be highly durable and resistant to wear, since the purpose of the plug-in arrangement is to permit ready replacement of the component, and the portion of the connector installed permanently in the permanent piece of equipment into which the component is plugged must desirably be capable of receiving a long series of replacement components without impairing the firmness of the electrical contact or the security of any mechanical support which is given the plugged-in component by the plug and socket arrangement.

The present invention provides a resilient hermetically sealed insulated electrical connector of a novel construction which assures highly secure electrical contact for a large number of successive plug-in components, but which is nevertheless simple and inexpensive to construct. The embodiment of the invention to be described illustrates the invention as applied to a plug-in precision potentiometer in which both the potentiometer and the socket into which it is plugged are hermetically sealed.

For understanding of the invention, reference is made to the attached drawing in which:

FIGURE 1 is a side elevation, partially broken away in section, of a plug-in potentiometer along with an hermetically sealed socket made in accordance with the invention;

FIGURE 2 is a sectional view taken along the line 2-2 of FIGURE 1;

FIGURE 3 is an enlarged sectional view taken along the line 33 of FIGURE 2;

FIGURE 4 is an enlarged sectional view, partially in elevation, of a contact member constituting a portion of the socket; and

FIGURE 5 is a sectional view taken along the line 55 of FIGURE 4.

As seen in FIGURE 1, the potentiometer, generally designated by the numeral 10, has the usual operating shaft 12 and a mounting flange 14. The shaft 12 is rotatable in a fluid-tight seal which is not illustrated, since it constitutes no part of the present invention. The back of the potentiometer is a header consisting of a steel plate 18 having glass inserts 20 in which are sealed tubes 22 of suitable high-nickel steel, the tubes in turn being 3,007,130 Patented Oct. 31, 1961 2 sealed by solder 24 which secures the internal leads 26 of the potentiometer within the tubes or male contacts 22. The plate 18 is suitably sealed to the open back of the potentiometer to form a completely sealed enclosure.

The three contacts 22 of the male connector on the potentiometer are seated in corresponding female socket connectors, generally designated 28, in a socket or header generally designated 30 sealed to the enclosure 31 of the equipment to which the potentiometer is connected. The socket header 30 employs a suitable steel plate 32 having glass-seal inserts 34 into which are sealed tubes 36 of a material such as that of the contacts 22.

In each of' the tubes 36 is a female contact 38" of a construction best seen in FIGURES 4 and 5. The female contact 38 has at one end thereof a pair of more or less semi-circular fingers 40 formed by the cutting of longitudinal slots 42 after the making of a longitudinal bore 44-. The internal surfaces of the fingers 40 are flared at 45. A small clearance (not visible in the drawing) exists between the outer surfaces of the fingers 40 and the inner surfaces of the tubes 36 prior to insertion of the male contacts to permit the spring action of the fingers to securely grip the male contacts upon insertion.

Adjacent to the fingered end portion is an elongated neck portion 46 of substantially reduced transverse dimensions, terminating in a short shank 48 of the same outer dimension as the outer dimension of the fingers 40, and terminating in an enlarged cap portion 50 forming a shoulder at 52. A well or bore 54 in the cap portion 50 serves as a soldering receptacle for the attachment of leads (not illustrated) within the hermetically sealed enclosure 31 to which the female header or socket is secured.

All portions of each of the contact members 38 other than the cap portions 50 are encased in the corresponding tube 36, the shoulder 52 being secured to the end of the tube by braze 56 to complete the seal.

Both the materials of construction and the manner of assembly must be carefully chosen in order to assure the proper hermetic properties and firmness of electrical contact. The materials of the metal base or plate 32, the glass inserts 34 and the tubes 36 are the materials commonly used in glass-to-metal seals, such as B-1113 steel for the plate, a suitable high-nickel steel alloy such as Driver-Harris #52 for the tubes, and any suitable matching glass for the insert. The contact members 38 are made from annealed beryllium copper. They' are silver brazed into the tubes with a brazing material which flows at a temperature slightly higher than 625 degrees F. Thereafter, the entire assembly is heat-treated in accordance with the hardening treatment prescribed for the particular beryllium copper which is employed, normally about 3 hours at 600 degrees F., but in any event below the fusion temperature of the braze. The braze must accordingly be properly selected, a suitable material for the purpose being a silver solder such as Silvaloy Alloy 45 employed with #1200 Universal flux.

The reduced diameter of the neck portion 46 on the female contact member aids greatly in simplifying the proper assembly of the connector in the manner described above. It minimizes the transfer of heat employed in the silver soldering operation to the glass insert 34, and thus minimizes the possibility of cracking of the glass due to differential heating in the soldering operation. By the same token, the necessary heat input for the soldering or brazing operation is minimized, since the constriction reduces the effective heat capacity of the assembly. The constriction also prevents capillary migration of the braze material to the fingers in the brazing operation.

The total enclosure of the fingers Within the tube maximizes the life of the spring prongs by providing a rigid backing limiting their outward bending and protecting them from accidental deformation.

In accordance with the provisions of the patent laws, there has herein been described a single embodiment of the invention. Many other embodiments, far different both in appearance and in details of construction, will be devised by persons skilled in the art upon study of the basic principles of the invention. Accordingly, the scope of the patent protection to be afforded should not be limited by the particular embodiment shown, but should be determined only from the description of the invention contained in the appended claims.

What is claimed is:

1. Aninsulated hermetically sealed female electrical connector comprising a body of glass, a tube of highnickel alloy of substantially the same temperature coefficient of expansion as the glass extending through the glass and sealed thereto, and an elongated contact member of beryllium copper having a first end portion comprising a plurality of fingers, a neck portion of substantially reduced transverse dimensions adjacent to the end portion, a shank portion of substantially the same transverse dimension as the first end portion adjacent to the neck portion, and a second end portion of enlarged transverse dimensions adjacent to the shank portion and forming a shoulder therewith, said first end, neck and shank portions being seated within the tube and said shoulder being seated against the end of the tube and sealed thereto.

2. A unitary female contact member having a first end portion comprising a plurality of fingers, a neck portion of substantially reduced transverse dimension adjacent to the end portion, a shank portion of substantially the same transverse dimensions as the first end portion adjacent to the neck portion, and a second end portion of enlarged transverse dimensions adjacent to the shank portion and forming a shoulder therewith, whereby the fingers may be inserted into a tube and the shoulder brazed to the end of the tube without disposing solder on the fingers and with a minimum of heat transmission to the first end portion.

References Cited in the file of this patent UNITED STATES PATENTS 2,344,280 Beggs Mar. 14, 1944 2,502,302 Arson Mar. 28, 1950 2,520,663 Tromp a- Aug. 29, 1950 2,563,760 Uline Aug. 7, 1951 2,638,573 Gliekman et a1. May 12, 1953 2,753,534 Sprigg July 3, 1956 

